Brand: Orion Telescopes USD

Orion GiantView™ 31x100mm BT45-deg Binocular Telescope (w/case) (51849)


Brand: Orion Telescopes USD

Orion GiantView™ 31x100mm BT45-deg Binocular Telescope (w/case) (51849)


  • Huge 100mm objective lenses and 28mm field stop diameter provide incredibly bright and immersive views of starry skies and daytime scenes
  • Included pair of 18mm, 65-degree eyepieces provide 31x views out of the box
  • Accepts interchangeable 1.25" eyepiece pairs for a variety of magnification options (additional eyepieces sold separately)
  • Features nitrogen purging, comfortable 45-degree eyepiece orientation, and individual eyepiece focusers
  • Weighs 14.5 pounds
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$2,099.95 USD

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Special Order
$2,099.95 USD

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Product Description

With two huge 100mm objective lenses, the Orion GiantView BT-100 delivers an immersive observing experience unlike any other.

Stargazing with both eyes brings an amazing amount of depth to each view while also making observations more relaxing and comfortable. Views of everything from lunar craters to wispy nebulae will take on an almost 3-dimensional feel in the GiantView BT-100 Binocular Telescope. This impressive instrument's 100mm (3.9") aperture objective lenses gather over 56% more light than large 80mm astronomy binoculars, so you'll be able to see more objects in the sky with greater clarity. But the fun doesn't stop at sunrise! During the day, this big binocular telescope becomes the ultimate "spotting scope" for terrestrial exploration. Set the BT-100 up on your deck or at your favorite scenic overlook to enjoy awesome long-distance views. The 45° angle eyepiece holders make both daytime and nighttime observations comfortable.

The GiantView BT-100 Binocular Telescope includes a pair of 18mm 65° flat-field 1.25" eyepieces which provide 31x magnification and a 2.13° field-of-view right out of the box. The included eyepieces are threaded for use with like-sized filters which can be used to enhance observations (eyepiece filters sold separately). Individual eyepiece focusers provide precise focus control, while compression rings hold inserted eyepieces securely in-place.

One of our favorite features of the BT-100 is its ability to accept pairs of interchangeable 1.25" eyepieces so you can control magnification depending on your observing goals (requires two 1.25" eyepieces of the same focal length and optical design, sold separately). For example, a pair of 10mm eyepieces will deliver a 55-power view through the 550mm focal length BT-100 (550/10 = 55). For the best results, we recommend using pairs of 8mm or longer focal length 1.25" eyepieces with the GiantView BT-100.

Since the GiantView BT-100 accepts 1.25" eyepieces, you can also use pairs of 1.25" light pollution filters to significantly improve contrast while observing nebulas and other interesting deep sky objects. With optional light pollution filters installed, the GiantView BT-100 provides seriously amazing views of the Orion Nebula and many more deep sky delicacies. (UltraBlock and SkyGlow light pollution filters sold separately.)

Thanks to its sealed construction and nitrogen purging, the rugged BT-100 is waterproof for use in damp conditions, but it's not designed for permanent outdoor installation. Bring these big binos inside after each viewing session to keep them in tip-top condition for peak performance year after year.

The big GiantView BT-100 Binocular Telescope weighs in at 14.5 lbs. and requires a sturdy binocular mount for stable support. A built-in threaded 1/4"-20 socket allows secure mount or dovetail plate attachment.

Note: Standard field tripods are not recommended for use with the GiantView BT-100. Includes hard foam-lined carry case.

What's in the Box

  • Orion GiantView BT-100 Binocular Telescope
  • Two 18mm wide-angle 65° 1.25" eyepieces
  • Two objective lens caps
  • Two eyepiece caps
  • Internal focuser plugs
  • Hard foam-lined carry case


Best for viewing Lunar & bright deep sky
User level Advanced
Magnification 31x
Optical diameter 100mm
Field of view - angular 2.1°
Field of view - linear 111.7 ft./1000 yd
Apparent field of view 65.0°
Eye relief 17.0mm
Exit pupil 3.2mm
Near focus 80 ft.
Coatings Fully multi-coated
Prism BAK-4 Porro
Interpupillary distance range 54mm - 76mm
Focus style Individual eyepiece focus
Waterproof Yes
Tripod adaptable Yes
Diopter adjustment Yes
Weight 14.5 lbs.
Additional included accessories
  • 45 degree eyepiece angle
  • Interchangeable 1.25" eyepieces
  • Compression lock focuser
Other features
  • Two 18mm Ultra Flat Field eyepieces
  • Dust caps
Warranty One year

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